OPM_LPS_33E_10K_30K_4CN_V010.doc 13/82 Operating Manual LP 33 / 10-20-30 kVA
Automatic bypass operation
In On-line operation mode, the load is
permanently supplied by the inverter but, in
case of trouble on the inverter, or when
overload or short-circuit on the output occur, if
the mains voltage do not exceed the admitted
tolerances, the load is instantly transferred to
the mains through the automatic bypass,
taking advantage of the higher short circuit
power.
Fig. 3.2-3 Energy flow in automatic bypass operation
When the inverter recovers, the load will be re-transferred automatically to the inverter.
In case of parallel system
Each unit has its own bypass.
All the bypasses in the system work together, their control being managed in the same manner
by all units.
The units are continuously exchanging information before taking such decision.
In case the inverter of one unit fails, its bypass remains operating.
It is excluded only if the unit is separated from the common bus by opening its output switch Q1.
Mains recovery operation
As soon as the mains recovers, the rectifier
starts up automatically supplying the inverter
and the battery-charger recharges the
battery.
In case the inverter has been shut down
following a complete discharge of the battery,
when the mains recovers the system start up
automatically.
Fig. 3.2-4 Energy flow at mains recovery operation
When the energy stored in the battery is sufficient to ensure a minimum time of operation with the
actual load, in case of a future mains failure, the load will be retransfered to inverter (if selected
On-line mode).
In case of parallel system
When the AC input power recovers, the rectifiers will start up sequentially according to their
number in the parallel system in order to avoid an initial inrush current.
The inverters will start up automatically, but only when the battery has recharged enough
for a minimum runtime with the present load.
When enough inverters to supply the load have been restarted, the load will be transferred
from the automatic bypass back to the inverter busbars.
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